1. Field of the Invention
The present invention relates to a wiring substrate, a method of manufacturing a wiring substrate and a liquid droplet ejection head, and more particularly, to a wiring substrate, a method of manufacturing a wiring substrate and a liquid droplet ejection head for achieving high-density wiring by forming wires respectively in a recess section and a projecting section.
2. Description of the Related Art
In the related art, it has been sought to reduce the size and weight of various electrical devices. For example, there have been demands for reducing the size and increasing the density of inkjet heads used in inkjet recording apparatuses, and the like.
In order to reduce the size of equipment, it is necessary to arrange the electrical wires which supply signals for driving the semiconductor elements, or the like, at a high density. Various technologies for manufacturing high-density wiring substrates have been proposed for accomplishing such high density wiring.
For example, a printed wiring substrate is known in which a first conducting layer is formed by electroless plating on the surface of a three-dimensional molding object made of an insulating resin which is formed with projecting sections and recess sections by extrusion molding, the surface is ground mechanically, a first conductive pattern is formed in the recess sections (grooves), and a wiring layer is formed in the recess sections (grooves) by forming a second conductive layer by electrolytic plating (electroplating) on the first conductive pattern. Furthermore, Japanese Patent Application Publication No. 2002-290010 discloses a printed wiring substrate which is manufactured as follows. A first conductive layer is formed by electroless plating on the surface of the three-dimensional molding object; whereupon a resist pattern is formed on a first conductive layer on the projecting sections; etching is carried out using the resist pattern as a mask; the resist pattern is peeled away so that a first conductive pattern is formed on the projecting sections; and whereupon a second conductive layer is formed by electroless plating on top of the first conductive pattern so that a wiring layer is formed on the projecting sections.
Furthermore, for example, Published Japanese Translation of PCT Patent Application, No. 60-502233, discloses a method of manufacturing a printed substrate in which grooves are formed in a substrate, the grooves in the substrate are filled with a conductive powder, pressure is applied to compress the powder in the grooves of the substrate, and the compressed powder is heated inside the grooves so that conductive channels (wires) are formed in the grooves in the substrate.
However, in the related arts described above, wires are only formed on either one of the recess sections or the projecting sections of the substrate, and wires are not formed simultaneously on both the recess sections and the projecting sections. Furthermore, patterns are formed by lamination. For example, if wires are formed only in the recess sections of the substrate, then it is difficult to achieve finer wiring or higher density. Furthermore, in a case of such lamination structure, the process is highly complicated, leading to increased costs or increased thickness.